u.s. government about the test beforehand. and even china, north korea's sole ally, has urged pyongyang to stop before it makes matters worse. >> tensions are high in south korea. protesters denounced north korea's nuclear tests. north korean state media claim the country had exploded a more powerful bomb than it had been able to build a earlier. diplomats at the united nations security council emergency meeting also expressed alarm. >> countries around the world, including every member of this security council, agreed that this test was an extremely regrettable act that further undermines international peace and security. >> many countries will likely impose new sanctions against north korea, but observers say that china has the most leverage. >> for china, it will depend on showing that north korea has gone too far this time and it will not go without consequences for the north korean-chinese relationship. i expect that china will also decide on painful sanctions for north korea. >> chin